AJS & Matchless Owners Club

Hello, I am new to the forum and new to forums in general, so please forgive my inept methods early on!
I have recently acquired a 1954 G3LS as a non-runner with various parts missing but nothing too serious. My question relates to the fact that it is missing its carburettor and magneto. Normally this would just require a bit of research, find the parts and away you go, but in my case the bike has at some time been converted to 500cc which gives me the dilemma of Do I buy a carb for a 500cc and see how she runs? Should I really just take it back to a 350cc and buy the carb for that? I suppose the advice I am really asking is would a 500cc be a better/nicer bike to live with? I have not yet had the head and barrel off to check for wear etc, but just assuming I find that all is apparently well with the condition of the 500cc barrel & head, what would someone who has experience with these machines do? Any advice or opinions appreciated, as I have never owned an AMC machine before, or indeed a 500cc single! Thank you.

That was a very common modification, back in the day... It was so easy to do.
If you keep it as a 500, then you'll want a carburettor set up for a 500, obviously.
I have both a 350cc G3/LS and a 500cc AJS M18S. Personally, I like the 350 better in some respects and love riding it but the 500 has more power and doesn't slow down so much when you come to a hill or ride into a head wind. You do notice hills and headwinds on the 350.

I would strip it down first, see if all is ok with the 500 bits. Then make your choice. For the 500 you will need a carb, 1 3/4" exhaust system, 5 plate clutch, 21T engine sprocket, SR1 magneto and auto advance and magneto chaincase with bulge. The 350 would have had an N1 Mag, flat chaincase, 18T engine sprocket, 4 plate clutch, pre-monobloc carb and a 1 1/2" exhaust system. I can see lots of parts list scrutinising ahead!
Dave.

The second best place on the internet for help with these machines is http://www.archives.jampot.dk/, workshop manuals, owners manuals, part manuals and more.

Hello Dave, thank you for your input. I can say it has the 1 3/4" Exhaust and 21t Engine sprocket, not sure about the clutch as I have not checked. Regarding the magneto is it essential to use the SR1 with auto advance? The bike did come with an assortment of spares including both types of mag chain case, but if I'm honest I do prefer the look of the flat case with the Lucas N1. Is it possible to use an N1 with manual advance/retard? Thank you!

Thank you Bob & Pharisee for your help and insight, I have got some lockdown decision making to do!

No it doesn't have to be an SR1. An N1 will be fine.
Dave.

Does anybody recommend a specific Amal carb for the 500? Does the year of the engine make any real difference to carb choice (1954)? I am not worried about originality given the bike has already had a capacity change. Thank you.

Hi

Check out the Burlen, (Amal) website:

http://amalcarb.co.uk/carbspec/carburet ... s/id/6665/

I've linked a vehicle search G80 1954

Regards Mick

Boycey wrote:Does anybody recommend a specific Amal carb for the 500? Does the year of the engine make any real difference to carb choice (1954)? I am not worried about originality given the bike has already had a capacity change. Thank you.

Personally, I'd fit a Monobloc rather than the remote float chamber type. My '55 M18S is fitted with 1.5/32" Monobloc and runs very well indeed.
They are available from the club spares and will be jetted for your engine... assuming that you tell them what it is.